import 'package:flutter/material.dart';
import 'package:flutter_logger/flutter_logger.dart';

// 这个类是新建工程时候默认的页面
void main() {
  runApp(new MaterialApp(
    title: 'Flutter Demo Home Page',
    theme: new ThemeData(
      // This is the theme of your application.
      //
      // Try running your application with "flutter run". You'll see the
      // application has a blue toolbar. Then, without quitting the app, try
      // changing the primarySwatch below to Colors.green and then invoke
      // "hot reload" (press "r" in the console where you ran "flutter run",
      // or press Run > Flutter Hot Reload in IntelliJ). Notice that the
      // counter didn't reset back to zero; the application is not restarted.
      primarySwatch: Colors.blue,
    ),
    home: new MyHomePage(),
  ));
}

/// 有状态的控件 可以做交互的处理
class MyHomePage extends StatefulWidget {
//  MyHomePage({Key key, this.title}) : super(key: key);

  // This widget is the home page of your application. It is stateful, meaning
  // that it has a State object (defined below) that contains fields that affect
  // how it looks.

  // This class is the configuration for the state. It holds the values (in this
  // case the title) provided by the parent (in this case the App widget) and
  // used by the build method of the State. Fields in a Widget subclass are
  // always marked "final".

//  final String title;

  @override
  _MyHomePageState createState() => new _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0; //前面加_表示私有的

  @override
  Widget build(BuildContext context) {
    // This method is rerun every time setState is called, for instance as done
    // by the _incrementCounter method above.
    //
    // The Flutter framework has been optimized to make rerunning build methods
    // fast, so that you can just rebuild anything that needs updating rather
    // than having to individually change instances of widgets.
    return new Scaffold(
      appBar: new AppBar(
        // 返回按钮我自己加上去的
        leading: new IconButton(
            icon: new Icon(Icons.keyboard_arrow_left),
            onPressed: () {
              print('返回首页');
              // 返回上一个页面
              Navigator.of(context).pop();
            }),
        // Here we take the value from the MyHomePage object that was created by
        // the App.build method, and use it to set our appbar title.
//        title: new Text(widget.title),
        title: new Text('Flutter Demo Home Page'),
      ),
      body: new Center(
        // Center is a layout widget. It takes a single child and positions it
        // in the middle of the parent.
        child: new Column(
          // Column is also layout widget. It takes a list of children and
          // arranges them vertically. By default, it sizes itself to fit its
          // children horizontally, and tries to be as tall as its parent.
          //
          // Invoke "debug paint" (press "p" in the console where you ran
          // "flutter run", or select "Toggle Debug Paint" from the Flutter tool
          // window in IntelliJ) to see the wireframe for each widget.
          //
          // Column has various properties to control how it sizes itself and
          // how it positions its children. Here we use mainAxisAlignment to
          // center the children vertically; the main axis here is the vertical
          // axis because Columns are vertical (the cross axis would be
          // horizontal).
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            new Text(
              '按下了按钮多少次：',
            ),
            new Text(
              '$_counter',
              style: Theme.of(context).textTheme.display1,
            ),
          ],
        ),
      ),
      floatingActionButton: new FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
//        child: new Icon(Icons.add),
        child: new Icon(Icons.add),
      ), // This trailing comma makes auto-formatting nicer for build methods.
    );
  }

  //回调里面的逻辑处理
  void _incrementCounter() {
    setState(() {
      //这个方法处理控件状态改变
      // This call to setState tells the Flutter framework that something has
      // changed in this State, which causes it to rerun the build method below
      // so that the display can reflect the updated values. If we changed
      // _counter without calling setState(), then the build method would not be
      // called again, and so nothing would appear to happen.
      _counter++;
      new Log("tag").d('点击了按钮');
    });
  }
}
